Studying On Seepage, Stability And Timbering Optimization Of Water Power Station Underground Workshop

The project of seepage controlling, stability analysis of underground cavern group, and optimizing of by-stage excavation and anchored-supporting for water conservancy and hydropower station was one of key problems in engineering field. Rock or rockmass structure and its existing state and condition were very complex and changeful, and underground workgroup and single opening for water conservancy and hydropower station were very big in size, thus, it had important academic meaning and practical engineering values to study deeply the finite element method for seepage and three-dimensional non-linear finite element method for stability analysis, and to choose reasonable seepage-control project, by-stage excavation and anchored-supporting project for underground workshop.Based on studying deeply the conditions of engineering & hydrological geology and properties of rockmass in Xiangjiaba water conservancy and hydropower station, according to the characteristic of seepage structure for rockmass, the computer program of finite element analysis for seepage analysis had been worked out by using the model of diplex cranny system, and the reasonable seepage-control project for underground workshop had been brought forward with using this computer program to analyze the anti-seepage and drainage effects of different combined form of anti-seepage purdah and drainage disposal. The optimization evaluation method of by-stage excavation had been proposed by using the magnitude of the plastic dissipation energy to evaluate different excavation orders, and it applied for the finite element analysis of the stability for underground workgroup and had been proved successful.Based on increment loading & changeable rigidity method and using three-dimensional non-linear finite element method and the elasticity-plasticity damage constitutive relation, the law of the effect of three different by-stage excavation scheme for multi-step excavation process on the stress disturbing, the plastic dissipation energy, the plastic region and the displacement around opening had been simulated and analyzed, and the project of excavation orders had been optimized and there were important engineering value.According to optimized excavation order for underground carven group, three anchored supporting scheme had been established. It is too simple to simulate anchor bar effect by using accustomed bar element in numerical analysis before, so support utilities was simulated by using implicit expression element of anchor cable and anchor bar in this paper and the distribution of plasticity damage region, the stress distribution of anchor bar and anchor cableand the distribution of displacement on the edge of opening had been analyzed with three different anchored-supporting schemes. At last the reasonable anchored-supporting project was confirmed. It was indicated by both academic analysis and engineering practice that the method, which was proposed in this paper, of seepage and stability analysis for underground carven group of water conservancy and hydropower station was reasonable and effective, and there were significant practical engineering value.